We purchased and use these $5 Gel Cases for our iPads. I'm happy with them, more background is available on this post.
The 70 apps we're starting the year with in STEM class are linked on this Listly list. (More background)
We use and are using a variety of iPad apps in our class. Here are some we used in 2013-14!
Rocket apps: (also available as a printable PDF with QR codes)
AR apps we might be using:
Dr. Fryer's top 3 creation apps for the iPad are:
Apps we've used infrequently:
For more app recommendations, see: